1. Historical versus Current Distribution. Limestone salamanders (Hydromantesbrunus) were discovered in 1952 when an area of limestone outcrops in an unlikely region (relatively low elevation in a region that becomes extraordinarily hot and dry in summer and experiences prolonged summer drought) was targeted for search. A previously unknown population was found in an area of limestone talus. The species occurs only along a short section (about 16–17 km) of the Merced River, from the vicinity of the type locality on the main highway to Yosemite National Park west to a region known as Hell Hollow, and a short distance up the North Fork of the Merced River, between elevations of 365–760 m. A fossil (Late Pleistocene) vertebra belonging to a species of Hydromantes was recovered from a woodrat midden found outside the southwestern margin of the range of this species in the lower Kings Canyon at 1,280 m. It likely represents either this species or Mt. Lyell salamanders (H. platycephalus). If it is this species, its range was more extensive in the past (Mead et al., 1985).

2. Historical versus Current Abundance. There is no indication that the size of the range nor the density of this species has changed, but neither have there been any significant new discoveries of populations for many years.

3. Life History Features.

A. Breeding. Reproduction is terrestrial.

i. Breeding migrations. Unknown and unlikely.

ii. Breeding habitat. Likely to be in cracks and crevices below the surface in limestone talus.

B. Eggs.

i. Egg deposition sites. Oviposition sites are unknown.

ii. Clutch size. Unknown.

C. Direct Development. Egg deposition has not been observed, nor has development, but its close relatives undergo direct development. Ovarian eggs were enlarged (4.6 mm in diameter) in the holotype collected in late February (Gorman, 1954). Eggs probably are laid in late spring and develop over the summer.

D. Juvenile Habitat. Unlikely to differ from adult habitat use. Juveniles and adults typically are active at the same time.

E. Adult Habitat. There is a general association with limestone, but salamanders have been found on the surface under both slate slabs and irregularly shaped pieces of limestone. They have been found in small areas of moss-covered or barren talus (Tordoff, 1980), as well as in rock crevices and even in abandoned mine tunnels. The vegetation in the region where salamanders are found is mainly chaparral, with a scattering of xeric-adapted trees such as gray pine (Pinussabiniana), and with California laurel (Umbellulariacalifornica) in more mesic sites. In general, the habitat appears marginal for salamander occupancy, and yet four species are sympatric in this seemingly hostile environment. The species has been found on relatively level ground, but it is more typically encountered on steep slopes, where individuals use their tail to assist in locomotion (Gorman, 1954). Temperatures at which this species has been taken range from 10.0 ˚C–14.0 ˚C (mean 11.4 ˚C; Feder et al., 1982).

F. Home Range Size. Unknown.

G. Territories. Unknown.

H. Aestivation/Avoiding Dessication. Salamanders are present on the surface when the soil is moist and temperatures moderate to cool. The species is thus active throughout the winter, but as spring progresses they disappear from the surface, typically by mid April or earlier. However, they are probably active throughout the summer below the surface; an adult was found in July in an abandoned mine shaft near the type locality (D.B.W., unpublished observation).

I. Seasonal Migrations. Unknown and unlikely.

J. Torpor (Hibernation). Unknown and unlikely.

K. Interspecific Associations/Exclusions. Other amphibians known to be associated with this species include arboreal salamanders (Aneideslugubris), Hell Hollow slender salamanders (Batrachosepsdiabolicus), yellow-eyed salamanders (Ensatinaeschscholtziixanthoptica), and Sierra newts (Tarichatorosasierrae; Gorman, 1954).

L. Age/Size at Reproductive Maturity. Unknown.

M. Longevity. Unknown.

N. Feeding Behavior. Members of this genus have highly specialized tongue projection capability and can project the tongue both far and fast (e.g., Deban et al., 1997).

O. Predators. Unknown.

P. Anti-Predator Mechanisms. Unknown.

Q. Diseases. Unknown.

R. Parasites. Unknown.

S. Comments. This is the largest of the California species of this genus and differs from the other members of the genus in its relatively uniform coloration, consisting of a rich brown. It is the most genetically distinct of the three species (Wake et al., 1978; Jackman et al., 1997). General species accounts have been provided by Stebbins (1985), Gorman (1954, 1964, 1988), and Petranka (1998).

4. Conservation. The type locality of this species is along the main access route to Yosemite National Park, and any widening of the road would destroy habitat, which is already highly restricted. Limestone salamanders are listed as a state Threatened species by the California Department of Fish and Game (www.dfg.ca.gov) and are protected. Apparently, they are in no immediate danger. In 1975, a Limestone Salamander Ecological Reserve was established by the Department on 48 ha of land, including the type locality (Anonymous, 1980).